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End date: 2024 × Start date: 2020 × Has files: Yes × Subject: electron transfer ×

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Now showing 1 - 3 of 3
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    Engineering of Laccase CueO for Improved Electron Transfer in Bioelectrocatalysis by Semi-Rational Design
    (Weinheim : Wiley-VCH, 2020) Zhang, Lingling; Cui, Haiyang; Dhoke, Gaurao V.; Zou, Zhi; Sauer, Daniel F.; Davari, Mehdi D.; Schwaneberg, Ulrich
    Copper efflux oxidase (CueO) from Escherichia coli is a special bacterial laccase due to its fifth copper binding site. Herein, it is discovered that the fifth Cu occupancy plays a crucial and favorable role of electron relay in bioelectrocatalytic oxygen reduction. By substituting the residues at the four coordinated positions of the fifth Cu, 11 beneficial variants are identified with ≥2.5-fold increased currents at −250 mV (up to 6.13 mA cm−2). Detailed electrocatalytic characterization suggests the microenvironment of the fifth Cu binding site governs the electrocatalytic current of CueO. Additionally, further electron transfer analysis assisted by molecular dynamics (MD) simulation demonstrates that an increase in localized structural stability and a decrease of distance between the fifth Cu and the T1 Cu are two main factors contributing to the improved kinetics of CueO variants. It may guide a novel way to tailor laccases and perhaps other oxidoreductases for bioelectrocatalytic applications. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    Structure of Diethyl-Phosphonic Acid Anchoring Group Affects the Charge-Separated State on an Iridium(III) Complex Functionalized NiO Surface
    (Weinheim : Wiley-VCH, 2020) Wahyuono, Ruri Agung; Amthor, Sebastian; Müller, Carolin; Rau, Sven; Dietzek, Benjamin
    Cyclometalated Iridium(III) complexes, i. e. [Ir(C N)2(dppz)][PF6], bearing either two or four -CH2PO(OH)2 anchoring groups (IrP2dppz or IrP4dppz) are explored as photosensitizers for p-type dye sensitized solar cell (DSSC). The synthetic route is described and the iridium(III) complexes are characterized with respect to their electrochemical and photophysical properties. The modified anchoring ligand geometry exploited in this work not only alters the electronic nature of the complex (that is by destabilizing the LUMO energetically) but more importantly improves the grafting ability of the complex towards the NiO surface. The photoinduced long-lived charge separated state (CSS) at the NiO|IrPxdppz interface is of a different nature comparing the two complexes. For IrP2dppz and IrP4dppz the electron density of the CSS dominantly resides on the dppz and the C N ligand, respectively. The stability of the CSS can be correlated to the solar cell performance in NiO-based p-DSSCs, which yield conversion efficiencies which are among the highest in the class of iridium(III) complexes developed for p-DSSCs. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
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    Site-Selective Real-Time Observation of Bimolecular Electron Transfer in a Photocatalytic System Using L-Edge X-Ray Absorption Spectroscopy
    (Weinheim : Wiley-VCH Verl., 2021) Britz, Alexander; Bokarev, Sergey I.; Assefa, Tadesse A.; Bajnóczi, Èva G.; Németh, Zoltán; Vankó, György; Rockstroh, Nils; Junge, Henrik; Beller, Matthias; Doumy, Gilles; March, Anne Marie; Southworth, Stephen H.; Lochbrunner, Stefan; Kühn, Oliver; Bressler, Christian; Gawelda, Wojciech
    Time-resolved X-ray absorption spectroscopy has been utilized to monitor the bimolecular electron transfer in a photocatalytic water splitting system. This has been possible by uniting the local probe and element specific character of X-ray transitions with insights from high-level ab initio calculations. The specific target has been a heteroleptic [IrIII (ppy)2 (bpy)]+ photosensitizer, in combination with triethylamine as a sacrificial reductant and Fe3(CO)12 as a water reduction catalyst. The relevant molecular transitions have been characterized via high-resolution Ir L-edge X-ray absorption spectroscopy on the picosecond time scale and restricted active space self-consistent field calculations. The presented methods and results will enhance our understanding of functionally relevant bimolecular electron transfer reactions and thus will pave the road to rational optimization of photocatalytic performance.